How many amps does my house actually need?

Most people only think about their electrical service when they’re adding something to the house, and the question that comes up is always some version of “is my panel big enough?” The honest answer is that it depends on how you live in the house, not just its size. Here’s how to think about it.

What “amps” actually measures

Your electrical service is rated in amps, and that number is the ceiling on how much power the whole house can draw at once. A 100-amp service can deliver 100 amps; a 200-amp service, double that. It’s not about any single appliance, it’s about everything that might run at the same time.

The catch is that almost nothing in your house runs constantly or all together. So the rated size and the amount you actually use on a busy evening are two different numbers, and the gap between them is what a load calculation measures.

Why 200 amps became the default

Homes built before roughly the 1990s were often wired for 60 or 100 amps, and for the appliances of the day that was plenty. What changed is what we now plug into a house. Heat pumps, EV chargers, induction ranges, hot tubs, and air conditioning are all substantial electrical loads that older homes were never designed to carry together.

Two-hundred amps became the standard because it leaves headroom for that modern mix plus whatever you add next. When we upgrade a service, 200 amps is what we install by default, not because bigger is always better, but because it’s the size that stops you from being back here in five years. The full scope is on the panel and service upgrades page.

The signs your service is undersized

You usually don’t need a calculation to suspect you’re short. The house tells you:

• Breakers trip when two big appliances run together, the dryer and the microwave, say.
• The panel is full, with no open slots for a new circuit.
• You still have a 60-amp service or a fuse panel.
• You’re planning to add a heat pump, an EV charger, a suite, or a hot tub.
• Lights dim noticeably when the furnace or AC kicks on.

Any of these is a reason to have the service looked at. None of them, on their own, proves you need 200 amps, which brings us to the actual method.

How we figure out the real number

A load calculation is the arithmetic the BC Electrical Code lays out for exactly this. It adds up the demand from your major loads, square footage, heating, range, water heater, dryer, and any big additions, and produces the service size the house genuinely needs. It’s the same calculation we run before quoting an EV charger install, because the question is identical: does the service carry the load, or not?

The useful thing about the calculation is that it cuts both ways. Sometimes it confirms a house needs the upgrade. Just as often, it shows that a 100-amp service has more room than the homeowner assumed, and a new load can go on without upsizing at all, sometimes with a small load-management device to share capacity.

When you don’t need to upsize

This surprises people, so it’s worth stating plainly: adding an EV charger or a heat pump does not automatically mean 200 amps. We’ve done plenty of jobs where the calculation showed a 100-amp service had room, and we told the homeowner so rather than selling an upgrade they didn’t need. If the math says you’re fine, that’s the answer, and it saves you a few thousand dollars.

There’s also the option that isn’t a full upgrade at all. If your existing equipment is aging but the capacity is fine, what you may need is a service change rather than a service upgrade, new gear at the same amperage.

Bigger than 200?

For most single-family homes, 200 amps is the answer. A few situations call for more, a large home with electric heating throughout, a property with a shop or outbuildings drawing their own loads, or an acreage feeding several structures. In those cases we size the service to the whole property, which sometimes means a larger service or a subpanel arrangement. That’s common on rural and acreage properties across the Fraser Valley.

The bottom line

How many amps your house needs comes down to how much you actually run at once, and the way to find out is a load calculation, not a rule of thumb. Most homes land on 200 amps when they upgrade, but plenty don’t need to upgrade at all. Before we quote any panel work, we run the numbers so the recommendation is based on your house, not a guess. If you want that number for your own place, ask for a quote.